Ga. Jones et al., HIGH-PRECISION AMS RADIOCARBON MEASUREMENTS OF CENTRAL ARCTIC-OCEAN SEA WATERS, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 92(1-4), 1994, pp. 426-430
We report on the first sub-5 parts per thousand precision radiocarbon
dataset measured on single targets using accelerator mass spectrometry
(AMS). A 13 sample water column profile collected in the Canada Basin
(74-degrees-N, 150-degrees-W, 3850 m water depth) of the central Arct
ic Ocean in September 1992 has been analyzed in duplicate and the aver
age total precision achieved for the 26 targets is +/-3.2 parts per th
ousand. The reproducibility of the 13 paired analyses averages +/-4.8
parts per thousand as determined by a chi-square fit minimization for
a quality factor of unity, and +/-7.8 parts per thousand using ANOVA.
Eliminating two of the 13 paired analyses because of apparent outlier
behavior in one of the two analyses comprising the pair results in a t
otal precision of +/-3.2 parts per thousand, a chi-square fit of +/-3.
5 parts per thousand, and ANOVA precision of +/-3.5 parts per thousand
. Comparison with a recently published AMS C-14 profile from the same
basin suggests these data are accurate as well. Results show that the
deep waters of the Canada Basin have a renewal rate of 430 years, in c
omparison with 250 years estimated for the deep waters of the Eurasian
Basin. Although the major requirement of the World Ocean Circulation
Experiment (WOCE) for a radiocarbon analysis precision of +/-3 to 4 pa
rts per thousand for deep water samples can now be met with the AMS te
chnology available at the National Ocean Sciences AMS Facility at the
Woods Hole Oceanographic Institution for single-target analyses, a car
eful program of duplicate analyses should be included to insure the hi
ghest quality in the WOCE DELTAC-14 dataset.